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HK: Fachverband Physik der Hadronen und Kerne

HK 59: Instrumentation XVI

HK 59.3: Talk

Thursday, March 17, 2016, 17:15–17:30, S1/01 A3

Measurements of the mirror surface homogeneity in the CBM-RICH — •Elena Lebedeva and Claudia Hoehne for the CBM collaboration — II. Physikalisches Institut JLU Giessen

The Compressed Baryonic Matter (CBM) experiment at the future FAIR (Facility for Antiproton and Ion Research) complex will investigate the phase diagram of strongly interacting matter at high baryon densities and moderate temperatures in A+A collisions from 2-11 AGeV (SIS100) beam energy.

One of the key detector components required for the CBM physics program is the RICH (Ring Imaging CHerenkov) detector, which is developed for efficient and clean electron identification and pion suppression.

The CBM-RICH detector is being planned with gaseous radiator and in a standard projective geometry with focusing mirror elements and photon detector planes. One of the important criteria for the selection of appropriate mirrors is their optical surface quality (surface homogeneity). It defines the imaging quality of projected Cherenkov rings, and directly effects the ring finding and fitting performance. The global homogeneity has been tested with the D0 measurement. Local deformations e.g. by the mirror holding structure can be investigated with the Ronchi test and Shack-Hartmann method from which first results are discussed in this contribution.